1. Background of the Invention
The invention relates to a roller unit for calenders, planishers or the like, including a flex-compensated roller having a roller shell which is supported--for example, hydraulically--for the compensation of sags, and including a mating roller, whereby one of the rollers includes a surface engraving; the invention also relates to a method for the manufacture of such a roller unit.
2. Description of the Prior Art
Other supports such as, for example, electrically heated supporting elements are known in addition to hydraulic supports, these expanding to a greater or lesser degree as they are heated and, thus, enabling a compensation of the sag in such roller units.
Such roller units serve for pressure treatment of foils, webs and the like, whereby one of the rollers is provided with a great variety of surface engravings so that this roller only exerts partial pressures on the foils, webs or the like.
In order to keep the sag of the mating roller low, this mating roller is made either as a solid roller or as a hollow roller having a wall thickness which causes only slight sag. The mating roller may be provided with a system of bores for heating purposes.
The flex-compensated roller has, for example, a hydraulically supported roller jacket, whereby the flex compensation is either directly generated via hydraulic pressure or via hydraulically actuated bearing elements which are seated on a stationary yoke. Up to now, the mating roller has been provided with the surface engraving. In general, a plurality of different surface engravings are present for a calender, so that the engraved mating rollers must be changed given a change in production. The costs for such mating rollers are high because they are executed as solid rollers or as hollow rollers having a thick wall thickness, because appropriate bearing seats must be provided for bearing the mating rollers, and because these mating rollers are frequently heated and, accordingly, must include bores as well as connections for a heating means. When changing the engraved mating rollers, problems arise due to the weight and due to the difficult manipulability caused as a result thereof. Installation and dismantling of the engraved mating rollers are involved since both the bearing as well as the connections for the heating means must be installed or, respectively, dismantled.